Kinnosuke Ikezawa, frequently called Kin-chan by his friends, is a character defined by his unwavering optimism and passionate heart. As a high school student, he is a classmate of Kotoko Aihara, and the two share a place in the less academically distinguished class, a stark contrast to the genius Naoki Irie. His background is that of an ordinary student who struggles with his studies; he never gains acceptance into a university, and after finishing his senior year, he enters the workforce, eventually taking a job in the cafeteria at the college Kotoko attends.

In personality, Kinnosuke is loud, energetic, and relentlessly cheerful. He is often described as being similar to Kotoko in that he can be clumsy and not particularly book-smart, yet he possesses a powerful determination and never backs down from a challenge. His motivations are driven by deep-seated loyalty and affection. From their first year, he has been the most ardent admirer of Kotoko, expressing his love for her openly and without shame, despite the fact that his feelings are never reciprocated. He regards Naoki as his primary love rival and hates him for his cold treatment of Kotoko, though Naoki typically does not see Kinnosuke as a serious competitor.

Within the story, Kinnosuke serves as a faithful friend and a comedic foil to the emotionally reserved Naoki. He is often present to stick up for Kotoko when she is hurt or rejected, offering her a constant, if unwanted, source of affection and support. One of the most significant moments involving Kinnosuke occurs when his own earnest proposal to Kotoko indirectly prompts Naoki to realize his feelings and propose to her first, leaving Kinnosuke in despair. However, his love for Kotoko is so steadfast that her marriage to Naoki does not immediately cause him to give up on her.

His key relationships evolve significantly over the course of the narrative. While his connection to Kotoko remains a core part of his identity, his story ultimately leads him to Christine Robbins, often called Chris, an English woman who falls in love with him. Initially, Kinnosuke rejects Chris flatly, insisting that his only love is Kotoko, but he eventually begins to return her feelings and proposes to her.

Throughout the series, Kinnosuke undergoes a notable development. He matures from a somewhat hopeless and lovesick delinquent into a more responsible young adult with a clear direction in life. His story finds a happy resolution as he moves on from his unrequited love for Kotoko to build his own family, marrying Chris and eventually having three children. While he does not possess any special intellectual or physical abilities, his notable strengths lie in his incredible loyalty, his boundless energy, and his never-give-up attitude, which often endears him to the audience and allows him to grow beyond his initial role as the clueless, rejected admirer.